1. Field of the Invention
The present invention relates to a coupling apparatus for structural members, including a pair of couplers which couples structural members independent of each other with each other.
2. Description of the Related Art
It is known well to assemble a large construction by coupler a plurality of structural members independent of each other.
A truss construction, for example, is well known as that construction. Conventional truss constructions are assembled with a plurality of structural members independent of each other by coupling apparatuses that use welding or fixing members such as bolts and the like.
For example, Research Report of Shimizu Corporation (Vol. 65, 1997, 4) discloses a coupling apparatus for coupling a plurality of truss structural members with each other making use of bolts.
As shown in FIG. 17A, the conventional coupling apparatus includes nose cones 12 of stainless steel mounted on predetermined positions, or both ends of a tubular truss structural member 10 formed of CFRP (Carbon Fiber Reinforced Plastic) by, for example rivets not shown. Each of the nose cones 12 has a truncated-conical shape, and a high tension steel bolt 14 is screwed into the nose cone 12 from the inner hole of the tubular truss structural member 10. The portion of the shaft of the bolt 14 projected from the nose cone 12 is covered with an aluminum alloy collar 16. A fixing pin 14e is studded in the above described portion of the shaft of the bolt 14, and a longitudinal groove 16a extending in a direction in which the shaft of the bolt 14 extends is formed on the inner peripheral surface of the collar 16. The fixing pin 14e of the shaft of the bolt 14 projects into the longitudinal groove 16a on the inner peripheral surface of the collar 16.
The conventional coupling apparatus further includes a spherical node member 18. A screw hole 18a is formed at a predetermined position of the outer peripheral surface of the node member 18 as well as a recess 18b is formed at an inlet of the screw hole 18a. 
After the projecting end of the shaft of the bolt 14 is aligned with the inlet of the screw hole 18a at the predetermined position of the outer peripheral surface of the node member 18, the collar 16 is rotated in a predetermined direction. With this operation, the bolt 14 is also rotated in the predetermined direction together with the collar 16, thereby the shaft of the bolt 14 is screwed into the screw hole 18a. The shaft of the bolt 14 is continuously screwed until the fixing pin 14e thereof is accommodated in the recess 18b of the inlet of the screw hole 18a. When the fixing pin 14e has been accommodated in the recess 18b, the bolt 14 can not be rotated by the collar 16.
In the conventional coupling apparatus assembled as described above, compression force exerted between the tubular truss structural member 10 and the node member 18 is mainly supported by the collar 16, and tension force exerted between the tubular truss structural member 10 and the node member 18 is mainly supported by the bolt 14.
When a node member 18′, in the outer peripheral surface of which four screw holes are formed on one imaginary circle with a maximum diameter at the same intervals, is prepared, the one ends of the four tubular truss structural members 10 can be coupled with the node member 18′ as shown in FIG. 17B.
Further, when a node member 18″, in the outer peripheral surface of which two screw holes are formed at desired two positions, is prepared, the one ends of the two tubular truss structural members 10 can be coupled with the node member 18″ as shown in FIG. 17C.
An increase in size of a construction inevitably increases the number of structural members to be coupled with each other, which makes an assembling work for the construction being troublesome.
Moreover, in the above described conventional coupling apparatus, work for aligning the projected end of the shaft of the bolt 14 at the one end of the tubular truss structural member 10 with the inlet of the screw hole 18a at the predetermined position on the outer peripheral surface of the node member 18 is very troublesome, and work for rotating the collar 16 in the predetermined direction to screw the shaft of the bolt 14 into the screw hole 18a is also very troublesome. Further, after the bolt 14 is screwed into the screw hole 18a as desired, the bolt 14 cannot be released from the screw hole 18a. 
The troublesome work for assembling a construction using the conventional coupling apparatus as described above becomes more troublesome when the above assembling work is performed in an unstable environment, such as on a body floating on water, or in underwater, aerospace, or the like.
Moreover, in the above described conventional coupling apparatus, the assembling work becomes difficult unless dimensional accuracy is strictly controlled, and the assembling work becomes furthermore difficult when elements that constitute the structural member and the coupling apparatus are exposed to external environments of high temperature and low temperature, in which the elements are thermally expanded and contracted, for a long period.
Further, in the above environment, even after the assembling work is finished, the coupling apparatus is greatly deformed due to the thermal expansion and contraction of the elements that constitute the structural member and the coupling apparatus, thereby the coupling apparatus may be subjected to fatigue failure.
The present invention is derived from the above described circumstances, an object of the present invention is to provide a coupling apparatus for structural members which is simple in structure and can make assembling and disassembling work of the construction easy while the assembling and disassembling work is performed in the unstable environment, such as on the body floating on water, or in underwater, aerospace, or the like.
A further object of the present invention is to provide a coupling apparatus for structural members which is simple in structure, can make assembling and disassembling work of the construction easy even if the assembling and disassembling work is performed in the unstable environment such as on the body floating on water or in the underwater, aerospace, or the like, and even if the assembling and disassembling work is performed in the environment where the construction is exposed to high temperature and low temperature for a long time period, and further prevents the construction from generating a large amount of deformation and stress due to temperature expansion and temperature contraction.